Why turkey has the same name as Turkey
past participle adjective from feed (v.). Fed up "surfeited, disgusted, bored," is British slang first recorded 1900, extended to U.S. by World War I; probably from earlier phrases like fed up to the back teeth.
1788, short for Federalist; as colloquial for "official of the federal government," from 1916, especially, after 1930s, of FBI agents.
Any federal government worker or agent, esp in law enforcement or taxation: right up to the day the Feds dragged him into court (1912+)